1. Field of the Invention
The invention is directed to a thread handling device for use in lockstitch sewing machines.
2. Description of the Prior Art
U.S. Pat. No. 4,263,859 of Ralph E. Johnson for "Thread Handling System for a Sewing Machine", issued Apr. 28, 1981, discloses a thread handling system which includes a thread handling device with elongate members that serve to hold and to meter needle thread to a needle and looptaker of a lockstitch sewing machine. The system further includes a thread tensioner. Thread from a spool extends to the thread tensioner, and beyond the tensioner the thread extends to the thread handling device. Beyond the thread handling device, the thread extends to the needle. A takeup, which brackets the thread handling device, sets stitches and pulls thread through the tensioner. The takeup moves the thread in one direction in the thread handling device to a stitch position at one end of its operating range, and moves in the opposite direction free of thread to the other end of its operating range, after which thread in the device moves to a position of reengagement with the takeup to shorten the path for thread between the tensioner and needle such that a quantity of thread is thereby supplied for use by the needle and looptaker.
It is a prime object of the present invention to provide an improved thread handling device of the kind disclosed in the said patent of Ralph E. Johnson which functions with simplified structure to apply a light and substantially uniform frictional force to needle thread during movement of the thread therein.
It is another object of the invention to so construct a thread handling device of the kind described in said patent as to avoid the adherence to close dimensional tolerances, during manufacture and assembly thereof, as a requirement for the production of a device capable of finely controlling thread moving through it.
It is still another object of the invention to so construct a thread handling device of the kind indicated as to avoid the need therein for a movable thread engaging member and biasing spring for such movable member.
Other objects and advantages of the invention will become apparent during a reading of the specification taken in connection with the accompanying drawings.